Trepanation is a surgical procedure in which a circular piece of bone is removed from the skull by a special saw-like instrument called a trephine or trepan. The operation is also known as trephination or trephining. The English word “trepan” comes from the Greek word trypanon, which means “auger” or “drill.”

In standard medical practice, trepanation is occasionally performed by a neurosurgeon in order to relieve pressure on the brain caused by trauma, or to remove a blood clot from brain tissue.

In recent years, however, trepanation has been touted by a small group of alternative practitioners as a way to expand one’s consciousness through the increase of blood flow to the brain and opening the “third eye,” also known as the inner eye or eye of the mind.

Practitioners of kundalini yoga refer to the opening of the third eye, located in the middle of the forehead, as entry into a new and completely different dimension of reality.

Trepanation is the oldest surgical procedure known to humans; skulls of Cro-Magnon people estimated to be 40,000 years old have been discovered with circular holes as large as 2 in in diameter. The Incas of Peru are known to have performed trepanation as early as 2000 B.C.

It is thought that these operations were performed to treat people suffering from psychotic disorders, epilepsy, or chronic migraine headaches by allowing demons to escape through the hole in the skull.

The oldest written reference to trepanation comes from Hippocrates (c. 400 B.C.), whose descriptions of head injuries refer to it as a necessary treatment for skull fractures with bone fragments pushed inward and compressing the brain.

Celsus and Galen refer to Roman surgeons of the first century A.D. as performing trepanations with implements resembling carpenters’ drills. Trephines were refined in various ways through the Middle Ages, the Renaissance, and the eighteenth and nineteenth centuries.

It should be emphasized that trepanations were done by ancient, medieval, and early modern physicians to relieve pressure on brain tissue—not to perform surgery on the brain itself.

Care was taken not to penetrate the dura mater, which is the outermost of the three meninges or membranes that lie beneath the skull and form a protective cover for the brain and spinal cord. Historians of medicine estimate, however, that as many as 40 percent of patients died from infections following the procedure rather than from the surgery itself.

Contemporary interest in trepanation as a path to expanded consciousness goes back only to the 1960s.

Bart Huges, a Dutchman who was expelled from medical school in the early 1960s for failing his examinations and using marijuana, is generally considered the founder of alternative trepanation. Huges developed a theory that he called brainbloodvolume while he was smoking marijuana at a party on the island of Ibiza.

He noticed another guest standing on his head to increase the intoxicating effects of the drug. Huges concluded that the expansion of consciousness associated with hallucinogens results from an increased volume of blood in the brain.

Japanese Anatomical Illustrations of trepanation
Japanese Anatomical Illustrations of trepanation

He reasoned that the removal of a piece of the skull would allow an even larger amount of blood to enter the brain, speeding up the delivery of oxygen and glucose to the brain cells as well as the removal of toxins.

Huges had also learned in medical school that infants are born with soft spots in the skull known as fontanelles, which are membrane-covered areas where the bone has not yet completely formed. He concluded that trepanation would help to return an adult’s consciousness to the intense imagination and vivid dreams of a child.

Huges—who never obtained a medical degree—managed to convert several individuals to his brainbloodvolume theory—among them Peter Halvorson, who underwent trepanation and credits it with curing his depression, increasing his energy level, and giving him a permanent drug-free high. As of 2004, Halvorson is the head of the International Trepanation Advocacy Group (ITAG), headquartered in Wernersville, Pennsylvania.

The ITAG web site includes accounts of a pilot study of six volunteers who were trepanned in June 2002 as well as personal testimonials from others who have undergone the procedure.


According to the testimonials collected by Halvorson, trepanation confers the following benefits:
  • relief from anxiety, depression, and other mood disorders
  • feelings of freedom and serenity
  • a richer emotional life
  • greater ability to recall dreams on awaking
  • decrease in frequency and severity of chronic headaches
  • higher energy levels

Other people who have undergone trepanation, however, maintain that these benefits are only temporary and may be due to the placebo effect.

A man who performed trepanation on himself in 2000 reported to an interviewer from an online body modification journal that he had “come to the frustrating conclusion [four weeks after the procedure] that the trepanation has had no lasting effect ... Trepanation has no more physiological effect than any other trauma ... it does not do what many hope it will.”


Surgical trepanation

A standard trepanation—most commonly done to relieve pressure on the brain when a portion of the skull has been pushed inward—is performed with the patient under general anesthesia under sterile conditions.

The neurosurgeon cuts the scalp over the injured area, pulls back a flap of skin, and bores a hole in the underlying skull with a trephine. After the depressed bone has been removed together with any blood clots that have formed, the surgeon carefully cleanses the area and closes the incision.

Alternative trepanation

Some alternative trepanations have been performed by people on themselves, with friends to assist with the procedure. In the early 1980s, several people in England performed the entire operation on themselves, with others present to help only if an emergency arose.

The reason for this stipulation was to protect the others in the room from criminal prosecution for performing surgery without credentials. The trepanner typically shaved his or her head and injected a local anesthetic. He or she then made an incision in the scalp over the area to be trepanned.

Next, a hole between 1/4 and 1/2 in in diameter was cut in the skull with a foot-powered dental drill. The trepanner then removed the piece of skull, cleaned the incision, and bandaged it. The scalp gradually grew back over the hole, leaving only a small permanent indentation.

More recently, however, trepanners have allowed others to assist with the operation; the man who was interviewed for the online journal had three friends who covered the walls of his room with plastic sheeting, did part of the drilling, and rinsed out the incision from time to time with sterile saline solution. He reported that the entire procedure took about 3-1/2 hours.

The participants in the ITAG pilot study, however, went to a clinic in Monterrey, Mexico, for their trepanations. The ITAG web site states plainly that “Self-trepanation today is a very selfish act. It opens the door for no one and you’d always have to keep it a secret. The public mind can’t handle this. You’d be labeled ‘insane.’”

According to the ITAG web site, the surgeon who presently performs the procedures for Halvorson’s groups was trained in Texas and is board-certified in four countries (France, Spain, Mexico, and the United States). The trepanations take about 35 minutes to complete. The cost of the operation is $2400–$3600, not including travel and hotel fees.


People who have performed trepanations on themselves have prepared by assembling the needed equipment and setting aside a room in their house to serve as the operating room.

ITAG requires persons interested in trepanation (who must be 18 or older) to go through a period of mental preparation known as engramming, which Halvorson defines idiosyncratically as “becom[ing] thoroughly acquainted with the terminology of conscious expansion.”

In addition, the volunteers must sign an informed consent form and a protocol that indicates that they understand the procedure is considered experimental. They are given MRIs before and after the trepanation.


Mainstream medical professionals uniformly warn against alternative trepanation because it is an extremely risky procedure—particularly if done by amateurs—with no certain or permanent benefits.

Because scalp incisions bleed profusely, people who attempt to trepan themselves are likely to find that the flow of blood obscures their field of vision, thus increasing the risk of self-injury.

Side effects

The potential side effects of alternative trepanation are severe, even life-threatening; they include permanent injury or death from infections, stroke, direct damage to brain tissue, generalized encephalitis, epilepsy, or brain abscesses.

Research and general acceptance

Trepanation is not accepted as an alternative therapy by any mainstream physicians or surgeons in the United States or Canada. In addition to the dangers of the procedure itself, neurosurgeons who have studied the claims made for trepanation say that Huges’ brainbloodvolume theory is anatomically impossible.